This application requests continued support for a broad program of empirical and theoretical research on speech perception and spoken word language. The major goal of this project is to understand and describe how spoken words are recognized and how the initial acoustic-phonetic information in the speech signal interacts and makes contact with other knowledge sources to support spoken language understanding. The proposed research will involve behavioral studies of perception and memory with normal-hearing adults and hearing-impaired adults and children with cochlear implants, computational analyses of words in the mental lexicon using several large computerized lexical databases, and modeling studies to gain new knowledge about the perceptual cognitive processes that human listeners use in perceiving spoken words and sentences. The proposed studies are organized into four major projects: (1) spoken word recognition and the mental lexicon; (2) contextual variability in spoken word recognition; (3) perceptual learning of novel voices; and (4) individual differences and working memory. The findings from this project not only have important implications for speech and language processing in normal-hearing and hearing-impaired adults but will also contribute to developing a much stronger theoretical basis for new clinical research on understanding the enormous individual differences in outcome measures obtained from prelingually-deaf children after cochlear implantation.